Process of drying paper.



J. D TUMPKIYNS. PROCESS 0F DBYNG PAPER. APPLICATION FILED MAY 25. |908.

Patnted Aplz 11, 1916.

JOHN D. TOMPKINS, OF VALATIE, NEW YORK.

PROCESS OF DRYING PAPER.

Specification of Letters Patent.

Patented Apr. 11, 1916.

Applcationled May 25, 1908. Serial No. 434,935.

To all wlw/n 1f-muy conce-rn:

lle it known that I, Joux l). Tonrkixs, of Yalatie. in the county of Columbia and State of New York, have invented a certain new and useful Improvement inlroeesses of Drying Paper, and do hereby declare that the following is a full and exact description thereof.

My process relates ing of webs of paper.

'l` he process is carried out with very rapidity, while at the same time the product produced thereby possesses very nearly, if not quite, the-same qualities as paper which has been dried by the oldslow proeess of drying at lower tempe 'atures in the presence of atn'iospherie air. The paper produced is one of very great tensile strength and is-f'ree also from any 'very great internal strains due to uneven drying orshrinkine.

My process involves the drying of a traveling web of paper by simultaneously heating both sides thereof. I effect thisresult by applying to both surfaces of the traveling web of paper effective conductors of heat, apparatus to the continuous drybemg provided `for maintaining said conductors at the proper tem-k peratures to obtain the nl ost'etfectiv'c results. In general, the moist web of paper traveling lweb vis dried upon one heated sui'-,

fai-e alone` such a surface. in order to attain tht-"speed which l have been able to attain.

must be maintained at :l very imiclrliigher l use, 4resulting inz dannige y tenda-raturethan to the libers ol' the web andalso in ,theproduetion. .of unequal strains throughout the bodywot' thm-paper due to uneven drying. \\'hile-.thetemperatures whieh l apply to \lie.1ttvv-oi-slntfaees of` the paper l liml-itapi eferable 'toi use avhighei.l temperagreat is led vover the surface of aheated drunrand-a` 'ducing a layer of` air :do not difl'er. l nnrrliedlr. from oneanother. in n'1y,process c turev in the drum than I do in the metal belt, for the reason that the moisture in the inner surface of the web of paper, that is to say, the surface which is upon the drum, can only ese-ape by passing through the body of the web itself, while the moisture which is located on thecother or outer surface of the web of paper can readily escape through theA perforations in the metal belt to the outer air. It will, therefore, be seen that in order to secure an equal evaporation on both surfaces of the traveling web of paper, it would be desirable to maintain the temperature on the inner surface higher than the temperature at the outer surface, so as to produce a greater tendency toward evaporation at the former point than at the latter. Because of the location of a heated belt on the exterior surface of the travelingA web, the stratum of air adjacent to the metal belt and therefore. adjacent to the web of paper at `its outer surface, is heated to a higher temperature than would be the case were the heated metal belt dispensed with.' The heating ofthe layer of air in this way results in lowering its degree of saturation,

and consequently, enables it to take up a not, of course, assist in raising the temperature of the traveling web of paper for the purposes of e\l'aporating the water therein, nor would it produce an outerstratuni of air adjacent to the web of paper having'a lower degreeof saturation than the surrounding atmosphere, nor eouldthese re-A` sultsbe obtained by means ofa canvas belt or a belt made offany material notadal'ited to conduct heatveffectively', for thereason, that such a belt being a non-conductor ot' heat, would not assist in raising the tem-' perature of the water i-n the web, nor in proadjaeent to the outer surface of the traveling web of paper having a lower degree of vsaturation than the surrounding atmosphere. further very greatA disadvantage of the latter, type of belt islin the fact that it does not permit, to any great degree. the escape of the moisture or water vapor from the web of paper.' owing to its impervious nature.

heat the same. lAfter the bulk of water vvapor has thus been allowed to escape from the body of the web, the same is again led upon the surface of a succeeding drum Where the metal apron is again led into contact vwith its outer surface to continue the drying process by repeating the steps above described.- The web is again separated, the tnetal apron again pre-heated and the two ed manner and to other drums of the same character until the process of drying is entirely completed. c

The apparatus which I use in carrying out my process is shown in the accompanying drawings in which- Figure-1 is a longitudinal vertical section of one type ofapparatus that I may use; Fig. 2 is a transverse vertical section of the same apparatus; Fig. 3 is a detail thereof; Fig. 4 is a side elevation of the metal apron used; Fig. 5 is a side elevation of another type of machine which may be used; and Fig. 6 is a plan view of a fragment of the metal apron.

Referring to Figs. l to 3, a indicates a series of main drying drums carried by the supports b, each of which is provided with a means for heating the same such as a steam inlet pipe b and a steam exhaust c, the former being located at one end of each cylinder, and the latter at the other end. Between and above these cylinders are located a series of auxiliary heating cylinders d.. having similar steam inlet and exhaust pipesA e and f. y n

A traveling metal belt or apron g is adapted to pass around the auxiliary heating drums (Z and the drying drums a alternately. The lower portion of the belt g is guided and sustained by a series of idler rolls lz.. which may be heated or not as found desirable. One of these rolls may be iliade adjustable as shown at z' in Fig. 1, so as to ta ke up the slack in the belt. For propelling the belt g and the main drying drums a, a train of gears j is provided, every alternate one of which is located upon a shaft of one of the drying drums n, and the intermediate remaining ones being located between the gears on thc drying drums it; so as to pro- `pel the latter all in the same direction and at an equal speed. The traveling web ot' paper u is led into the n'iachine, as shown at the right of Fig. 1, over a guide roll 1 from upon a succeeding drum in the same which point it passes downwardly between the metal belt and the drying drinn at this portion of the machine. The web of papel' after passingaround this drum passes upwardly out of contact with the apron and drum and is led over a guide roll m located at one side of one of the auxiliary heating drums (I. Symmetrically placed on the other side of this auxiliary heating drum is a similar guide roll m for the paper' web. The rcmaining auxiliary heating drums (Z, with the exception of the one located at the back or end of the machine shown at the left of Fig. 1,are each provided with a pair of guide rolls m, similar to those already described. The last auxiliary heating roll is provided with a single guide roll n similarly located to the guide roll Z, located at the front of the machine.

Referring to Figs. 4 and 6 which show the construction of the metal belt, I find the most 'effective arrangement for this portion of my a paratus to consist of a number of curved p ates o hinged to one another at the points 72 by means of pintles f/ extending throughout the entire width of the metal belt. As shown in Figs. 4 and (i, the method by which I preferably hinge adjacent plates to each other, consists in curving the edges ofthe plates around the pintles at short intervals throughout the ad'acent edge ot' each plate, one plate being supported from said pintle for a few inches. then the adjoining plate being supported in the same. manner for a corresponding distance throughout the entire width of the belt. I have arranged the curvature of each plate so that it will fit closely to the traveling web ot' papel' while it is supported upon the drying drums (i, so as to obtain the maximum heating effect. I

lhave also arranged the size of the pintles f;

so that while the apron is passing around the heating drums (I, the central portion oi each plate 0 will be in contact with the periphery of th f drum. as will also the curved portions of each edge of the plate surrounding the pintles used for hinging one plate to the other. Inasmueh as each plate. therefore, contacts with the heating drum d along three diii'erent lines, a large quantity of heat can be conducted from the heating drum to the traveling apron. The plates o ot' the apron are provided with a plurality of openings or perforations 1' which may be ot' any desired shape or size.

The other modification. as shown in Fig. consists of a lower series of drying drums n. and an upper series of drying drums a?.

located intermediate of the members of the` lower series of drums.' The lower series of drying drums are providedwith a series of auxiliary heating drums (l. located in the same relation thereto as in the modification shown in Fig. 1. The upper series of drying drums a? are provided with a like seriesl lis of auxiliary drying drums d2, located in an analogous manner, thoughbelow instead of above the series of drums. AI train of gears j', similar to the gears j already described, is provided for rotating the lower drying drums af, and gears jz are arranged so as to -mesh with these to drive the. upper drying drums a2 through the agency of gears y'3. Idlers h. such as those shown in-Fig. 1, are

also provided for the lower series of drums a, and similar idlers h2 are located adjacent tothe upper series of drying drums a2, but above instead of below7 the drums. One of the idlers in each set on this machine is made adjustable, as shown at z" and 2, so as to take up the slack in each .of two aprons g and g2, traveling around the respective sets or series of drying drums. The traveling web of paper in this instance is led into the machine over a guide roll Z, shown at the right of Fig. 5, whence it proceeds around the first member of the lower series of drying drums, thence upwardly over the first member of the other series of drums, and then downwardly again to the next drum in the lower series, and so on until it has passed around all of the drums in the machine. During .the passage of the web of paper from one drum to another, each of the traveling belts or aprons gyand g2 is led around one of the auxiliary heating drums CZ and (Z2 so as to be pre-heated or reheated prepara tory to being led into contact with the outer surface of the traveling web of paper while it is supported upon the drying drums.

In either ofthe modified forms of the apparatus above described, the moist web of paper is led into the machine between a drying drum and the traveling metal belt or apron passing over the same, the drying drum being preferably, though not necessarily, maintained at a higher temperature than the Vtemperature of the metal apron while it is in contact with the web of paper supported upon the drum. The `web of paper is thus heated from both surfaces simultaneously, so that before.` it leaves one drum it has become effectively and thoroughly heated throughout its entire thickness. A The inner surface Vof the web, however, that is to say, the surface adjacent to the drying drum, is maintained at a somewhat higher temperature than the outer surface of the web of paper, for the `reason that it is much more difficult for the moisture to escape from the body of the paper next to the cylinder than it is from'the outer surface of the web of paper, inasmuch as the latter is constantly in contact with the outer air, whereas the moisture in other parts of the body of the web is compelled to pass through the web itself before escaping. The heated metal belt further maintains a stratum of highly heated air in contact with the outer surface of the traveling web of paper. A This stratum of air because of its high temperature, has a' lower degree of "saturation than has the surrounding atmosphere. Such being the case, the moisture from the web will evaporate much more rapidly and readily than were the air at this point notheated'. Again, from the fact that theweb is heated from both surfaces simultaneously, it follows that the p aper will dry and shrink much more evenly. This is very important, because in the case where the paper is heated from one surface alone, that surface will have a tendency to dry much more rapidly and shrink in a corresponding'ma-nner and consequently set up unequal strains throughout the body of the paper, resulting in a product which will have a much greater tendency -to tear than in the case where the web is dried evenly.

Provision is'made in may process for periodically allowing the web of paper tok come in contact with 'the air freely at both of its surfaces, so as to allow it to dry and shrink to the fullest extent possible and in as even a manner as possible. During these intervals, the portions of the metal aprons are preheated so as to raise them as nearly as possible to their ideal temperature before-passing around the drying drums.

lVhile I have described my process above in detail, I do not wish it to'be understood that I am necessarily limited to the details herein described, as Iy consider that many changes might be made withoutdeparting from the fundamental principles of my invention. The apparatus by means of which I carry out my process is also capable of many modifications. For example, I might heat the two surfaces of the traveling web of paper by means of any effective conveyer or conductor of heat, which terms I desire to be considered synonymous; that is to say, that I consider any method of effectively heating the two surfaces of the traveling y web of paper to come wlthin the purview of my invention. i

I claim:

1f.' The process of drying paper continuously, which comprises supporting through-l out a portion of its path a traveling web of paper upon a heated conductor of heat, while bringing into contact with the opposite surface of the web of paper through the same portion of the path a second heated conductor of heat, and then separat. ing the web of paper from both conductors of heat to obtain free lateral shrinkage.

Q. The process of drying paper continuously', which comprises supporting throughout a portion of its path a traveling web of paper upon a heated conductor of heat, while applying to the opposite surface of the web of paper through the same portion of the path a second heated conductor of heat, one of said conductors causing the continual free escape of moisture and then separating the web of paper from both conductors of heat to obtain free lateral shrinkage. y

8. The process of drying paper continuously, which comprises suppoi'tino' throughout a portion of its path a travellng web of paper upon a heated conductor of heat, while applying to the opposite surface of the web of paper through the same portion of the path a second heated conductor of heat, the first conductor being' maintained ata higher tennnrature than the second conductor and then separating the web of paper from both conductors of heat to obtain free lateral shrinkage.

l. The process of drying' paper continuously, which comprisessupporting throughout a portion of its path a travelingaveb ot' paper upon a heated conductor of heat. while applying' to the opposite surface of the'u'eb ot' paper through the same portion o't` the path a second heated conductor ot' heat. and separating the traveling' web of paper l'roin the eoluluetors so as to peruiit moisture to escape from both surfaces simultaneously and obtain free lateral shrinkage.

5. Thev process of drying paper continuously which comprises simultaneously heating both surfaces of a traveling web of paper by means of effective heated conduc-I tors of heat which travel in the same direction as and conform to the surfaces of the traveling' web of paper, and then separating' the web from the conductors of heat to obtain free lateral shrinkage.

(i. The process ot' drying paper continuously which comprises simultaneously heating both surfaces of the traveling,- web of paper by means of effective heated conductors ot' heat and then separatingr the web from the conductors of heat to obtain free lateral shrinkage, the conductor adjacent to one surface causing the continual free escape of moisture.

In testimony that I claim the foregoing I have hereunto set my hand.

'itnesses: 

